1. Field of the Invention
This invention relates to a slide fastener, and more particularly to a fastener stringer having a continuous plastic filament spirally formed and woven into an edge of a stringer tape during the weaving thereof by a needle loom.
2. Prior Art
There have been proposed a number of slide fasteners or zippers of the type described, which comprise a woven stringer tape and a plastic filament woven into a longitudinal edge of the tape, the filament being usually formed into a helical coil structure consisting of a succession of loops or elongated convolutions each having a coupling head, an upper and a lower leg and a connecting portion.
There are known two typical methods of making woven fastener stringers; one such method is to weave a continuous linear filament on a shuttle loom in a manner similar to a weft thread and formed, in the course of weaving, into a spirally-arranged interlocking structure, and the other method is to preform filament into a spiral or coil structure and interweave the same as the warp along an edge of the tape with double picks of a continuous weft thread on a needle loom.
While the shuttle weaving is advantageous in that the filament can be secured to the tape with a group of less bulky binding threads, the shuttle itself is necessarily small for handling fastener stringers and hence not suitable for producing an elongated, substantially endless slide fastener chain with reasonable speed. This drawback is eliminated by the needle loom operation which has however a difficulty in that the weave system which secures the filament to the tape becomes objectionally bulky and presents itself to be an obstacle to the movement of a slider, resulting in torn or worn tape threads.